Medical biotechnology, semiconductor, automated laboratory and other industries use containers, such as bottles, which store chemicals reagents, waste liquid and other materials. Such bottles have different shapes and sizes with irregularities and different construction at the bottom of each bottle. Also, sometimes these industries fill different types of liquid in the same bottle type or use different bottle types with the same type of liquid. In both cases, a user has no knowledge of the full/empty condition of a liquid in the bottle. This may damage or delay manufacturing and analysis processes due to lack of reagents not being known to be available or to cause overflow of the container if already filled completely, which possibly can be hazardous.
It is known in the art to use ultrasonic measuring systems to determine the level of a liquid in a container. When the container is large, such as an open tank, an invasive transducer is used in which a hole is made in the wall. An ultrasonic transducer is mounted in the hole and the transducer comes in contact with the liquid. Where the liquid is to be in a bottle, it is not usually possible to use an invasive transducer. Also, if the liquid in the bottle is to be kept in a sterile condition a transducer coming in contact with the liquid would spoil the sterility. In such cases, a non-invasive ultrasonic transducer is used. Such a transducer is usually mounted on the outside surface of the container by a mechanical arrangement or by an adhesive. It also requires the application of a coupling substance, such as a gel, between the transducer and the container surface. Therefore, mounting of a liquid level transducer either removably or permanently can be costly and time consuming.
Accordingly it would be advantageous to be able to provide an ultrasonic liquid level measuring system having a non-invasive transducer that can be used with containers of different shapes without having to mount the transducer to the container to achieve the measurement.